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Copy 1 



COMPARISON 



EXPERIMENTS 



AMERICAN AND FOREIGN BUILDING STONES 



TO DETERMINE THEIR 



RELATIVE STREi\GTH AND DURABILITY. 



Prof. WALTER R. JOHNSON, 

OF WASHIXGTOX, D. C. 



EXTRACTED FROM THE AMERICAN JOURNAL OF SCIENCE AND ARTS, VOL. XI, 
SECOND SERIES, JANUARY, 1851. 






NEW HAVEN: 

PRINTED BY B. L. II A ML EN, 

Printer to Yale College. 

1850. 



COMPARISON 



EXPERIMENTS 



AMERICAN AND FOREIGN BUILDING STONES 



TO DETERMINE THEIR 



RELATIVE STRENGTH AND DURABILITY. 

Prof. WALTER R. JOHNSON, 

OF WASHIXGTOX, D. C. 






EXTRACTED FROM THE AMERICAN JOURNAL OF SCIENCE AND ARTS, VOL. XT 
SECOND SERIES, JANUARY, 1851. 



NEW HAVEN: 

PRINTED BY B. L. HAMLEN, 
Printer to Yale College. 

1850. 



COMPARISON OF EXPERIMENTS, &c. 



As we have in the United States but few ancient buildings, the 
age of which can furnish conclusive proofs of the durability of 
their materials, and as but few of the materials which are found 
in such abundance and variety in this country, have been sub- 
jected to any satisfactory experimental tests to prove either their 
strength or durability, it is desirable that a rigorous comparison 
should be made, not only between the results of such trials on 
American rocks as have been made, but also between them, and 
such foreign materials as have been tested by the most careful 
experimenters, and have besides undergone the more decisive 
proofs of many centuries of use in public edifices and monu- 
ments. As nature has in many situations exposed these various 
materials to the direct action of all the causes which can work 
their gradual destruction, and as these destructive causes have evi- 
dently wrought v/ith an efficacy on some rocks vastly greater 
than on others, it is clear that if we would ascend to the highest 
and most reliable proofs of durability, we must seek for them in 
the condition which the rocks themselves have been able to 
maintain, not for the few brief centuries to which the memory 
of man extends, but during the geological ages which run back 
immeasurably beyond all human history. Those rocks which 
amidst the denuding, disintegrating and decomposing influences 
whether derived from sweeping currents of water, from meteoric 
actions and changes of temperature, or from vegetable growth 



4 Experiments on American and Foreign Building Stones. 

and decay, have been able to sustain themselves in high, bold, 
naked, angular chffs, unprotected by soil, and yet unfurrowed by 
irregular disintegration, are manifestly those to which the engi- 
neer and architect are to direct their attention, when they seek 
materials for durable works of art. On the other hand, they will 
shun those rocks which the causes above enumerated have kept 
constantly down to a level with the ground, or which barely rise 
in some few patches to the surface, and are there seen disintegra- 
ting, scaling away, and covering themselves with a soil derived 
from their own debris. 

The chemistry of geology furnishes to the architect and en- 
gineer most important hints for guiding their selection of materi- 
als; hints which when taken with other tests and proofs, leave 
them without excuse for choosing those of an inferior character. 
The influence of such a substance as iron pyrites on the durabili- 
ty of rocks in which it occurs, is so well known to every one ac- 
quainted with even the rudiments of geology and mineralogical 
chemistry, as scarcely to need a formal statement.* The effect 
of carbonic acid with water in dissolving carbonate of lime, and 
the readiness with which it acts on loosely aggregated crystalline 
masses of that carbonate, to effect their disintegration, may be 
understood from any elementary work on chemistry. The great- 
er solubility of sulphate than of carbonate of lime may be ascer- 
tained from the same source. The weakness of coarsely crystal- 
lized stones as compared with those of finer texture, is so well 
known as to be properly classed among the canons of architecture.! 

Of all the purposes for which building materials are employed, 
that which requires the utmost attention to durability is the erec- 
tion of national monuments. It is a mockery to the dead, and 
an opprobrium to the living to put perishable materials into struc- 
tures professing to perpetuate the virtue of great and good men. 
The Spanish nation is represented to have recently determined 
on the erection of a magnificent statue of bronze to rest on a 
base of rose granite, the most enduring of that species of rock, 
to commemorate the glory of Columbus. 

The question of the strength of a material to resist a crushing 
force is sometimes a vital one, as has been painfully proved within 
a year or two past in some of our large cities, where extensive 
warehouses have been crushed beneath their own weight and 
that of the goods which they contained, occasioning fearful losses 
of life. But the crushing test has by no means a single aim. It 
looks to the relation between the cohesion of a material and its 
capacity to resist the action of other than mechanical causes of 

* " Pyrites when present (in granite) renders tlie rock unfit for use, as it decom- 
poses and stauis or rusts tlie surface, besides loosening the grains and causing the 
rock to fall to pieces." — Dauas Minerah</i/, p. 579. 

f Borgni's " Constructions Diverses," p. 23, and Roudelet's " Art de Batii-," 



Experhnents on American a?id Foreign Building Stones. 5 

disintegration. It is certainly a most egregious mistake to con- 
struct any tall public edifice in such a manner as not to sustain 
its own dead weight, but there are operations scarcely less dis- 
creditable, and which apply with equal force to structures profess- 
ing to be enduring whatev^er be their height, their form, propor- 
tions or weight. 

The usual trial of materials in small cubes is intended to fur- 
nish the relative strength or durability of the several species of 
materials to which it is applied. 

The stone used in the Washington National Monument, and re- 
ferred to in the following comparisons of experiments, is the same 
as that mentioned under the name of -^ alum limestone,'' ' in the 
report of the building committee to the Regents of the Smithso- 
nian Institution, Dec. 7, 1847. 

" The marble quarries of Maryland, chiefly in the vicinity of 
the village of Clarksville, about thirteen miles from Baltimore, on 
the line of the Susquehanna Railroad, contain two qualities of 
marble ; one fine grained and of beautiful uniform color, ap- 
proaching the character of statuary marble ; the other of inferior 
quality, similar to the Sing Sing marble employed in New York 
in Grace Church and other public structures, of a somewhat coarse 
and highly crystalline structure, and known to the quarrymen 
here under the name of 'alum limestone.' "* 

Trials of these two kinds of stone by the the process of Brardf 
were made by Dr. Page in 1847, and shewed that "an inch cube 
of the fine-grained marble lost in four weeks about one-fifth of a 
grain ; and a cube of the best quality of the ' alum stone,' or coarse- 
grained marble from half a grain to a grain and a half^X 

This indicated with sufficient clearness the inferior durability 
of the coarse-grained stone ; since it underwent from tioo and a 
half to seven and a half times as much disintegration as the 
fine-grained variety. The fine-grained stone is understood to be 
derived from the Taylor quarries, half a mile westward of Cock- 
eysville, and about a mile distant from the Griscom lime quarries 
which are at a place called Texas, where the "alum limestone" 
used at the National Monument is procured. At the latter quar- 
ries the stone is worked wholly below the original surface of the 
ground. At a few points along the outcropping edge of the bed, 
the harder parts of the rock come to the surface of the ground 
or rise occasionally one or two feet above it, covered in places 
with loose granules of the same rock. In some parts it is eroded 
into sloping channels, lined with skeletons of crystals and their 
slightly cohering nuclei. 

On removing the soil, the rock is found with alternating peaks 
and cavities ; its surfaces are more or less deeply tinged with the 

* Hints on Public Architecture, bj R. D. Owen, p. 114. 

f Ann. de Chim. et de Phys., torn. 38. % Owen, p. 116. 



6 Experiments on American and Foreign Building Stones. 

oxyd of iron derived from decomposed iron pyrites, many veins 
of which traverse it in various directions, and the skeleton crys- 
tals with loosely cohering nuclei are even more conspicuous than 
at the points where the rock crops out as above described. 

That even the fine-grained stone above mentioned is not in 
all respects suitable to be employed as the casing stone of large 
shafts, is proved by the present condition of the shaft of the 
Washington Monument in Baltimore, where a similar stone from 
the same neighborhood was used. This monument was com- 
menced on the 4th of July, 1815, and the statue was elevated on 
the 19th of October, 1829. On the 23d of October, 1850, or 
twenty-one years from the date of its completion, I examined from 
the platform at the base of the shaft the condition of its lower part. 

There was seen on the side of the shaft opposite to the north- 
east corner of the base, a crack commencing near the bottom 
and following partly the joints of the masonry, and partly certain, 
transverse or vertical cracks crossing the blocks of marble. The 
3d, 5th, 8th, 10th, 11th, 13th, 14th, and 15th courses of stone, 
counting from the bottom, were seen to be broken either partly 
or wholly across, and in one instance a block is broken into three 
pieces. On the southeasterly side of the shaft is a second line 
of fracture crossing ten or twelve blocks, mostly alternating with 
the courses of masonry which have joints corresponding with the 
general course of the fissure. At the southwesterly side are 
fifteen blocks cracked either partly or wholly across, and form- 
ing a third fissure more or less in a zigzag direction, controlled 
apparently in some degree by the joints of the niasonry. On the 
west side a fourth line of fracture appears to ascend some forty or 
fifty feet, and on the northwest side still a fifth line perhaps some- 
what more irregular in direction than the preceding, but still 
easily traceable by the eye. In some cases where the cracks on two 
alternate blocks meet the joint of masonry in the course between 
them, the opening of that joint is apparent; in other words the 
crack is here in the cement, as might reasonably be expected. 
How long these cracks have existed, I have no means of ascer- 
taining. But one thing seems certain, that alternate cold and 
heat, rain and frost, will, along these lines of fissure, produce their 
usual effects of thrusting farther and farther apart the masses 
which bound them. Time will reveal the effects, and perhaps 
expose the causes of these incipient dilapidations. 

A chemical analysis of the "alum limestone" has been pub- 
lished by Dr. L. D. Gale, which makes the composition of that 
sample to be 

Carbonate of lime, .... 98-6 

Silica or other insoluble matter, . . 1-4 

100^ 



Experiments on American and Foreign Building Stones. 7 

I have also found one very white specimen in which the insoluble 
matter was only 0*4 per cent., but even from the solution of this, 
ammonia threw down a slight brownish precipitate of oxyd of iron. 

A specimen of the blue vein variety showed the following 
characters : — Its specific gravity was 2*708. 1218-4 grains pulver- 
ized and carefully washed, afforded a residue of 5b grains of iron 
pyrites (and an inappreciable quantity of adhering silica,) equal 
to 0-45 per cent. 100 grains treated with strong acetic acid, lost 
73-7 percent. Strong boiling nitric acid applied to the insoluble 
residue dissolved the pyrites, and the sulphuric acid thence pro- 
duced was precipitated with chlorid of barium, giving 1-62 
grains, equivalent to 0-42 grains of iron pyrites, agreeing very 
nearly with the mechanical analysis. 

The acetate was dried up, converted into carbonate and then 
redissolved and precipitated with oxalate of ammonia, to separate 
the lime, after which ammonio-phosphate of soda threw down of 
phosphate of magnesia 1-3 grains, equivalent to 0*47 grain of 
magnesia, or to 97 grains of carbonate of magnesia. From this 
it should seem that the sample was composed of 

Carbonate of lime, .... 72-73 
Carbonate of magnesia, . . . 0-97 

Sulphuret of iron, .... 0-42 

Insoluble silicates, .... 25-88 

100- 
As the pyrites is one of the chief coloring matters of the dark 
veins, it is evidently very variably distributed through the stone. 
The crystals of sulphuret are mostly small, but easily detected, 
by the naked eye. 

On breaking a weathered portion of the pyritons vein it is often 
found penetrated from one to two or three inches by the coloring 
matter (peroxyd of iron). On the interior parts of the discol- 
ored portion, the pyrites will be found but partially decomposed. 
On the outer portions it will have wholly given place to the per- 
oxyd. On the fresh surfaces not reached by rust, the yellow py- 
rites remains unchanged. 

When an attempt is made to polish a surface of the alum lime- 
stone, portions will occasionally be detected which from their 
softness render fruitless all attempts to impart lustre to them. On 
careful examuiation they will be found so soft as to be readily 
scratched with the finger nail. In many parts, little triangular 
cavities, from which it appears the last remnants of the solid an- 
gles of crystals have dropped out in the operations of cutting and 
polishing, will be easily discovered by the eye, and slight lines 
forming the boundaries of the large crystals are not unfrequently 
traceable when the piece is brought into a strong light. A block 
thus polished will have all its crystals of pyrites from their su- 



8 Experiments on American and Foreign Building Stones. 



perior hardness left slightly elevated above the surface of the car- 
bonate of linae which is worn away in polishing. 

The surface of polished stone thus variously marked with ele- 
vations and cavities, may be used like an engraver's plate, and 
will give an impression of its own markings, of much interest. 

1. Trials of two-inch cubes of the coarse-grained " alum 
limestone,^^ used at the National Washington Monument, to as- 
certain its resistance to crushing. By Dr. Charles G. Page. — 
The specimens were stated to have been furnished by the owner 
of the quarries, and the testing to have been performed by the 
aid of a " powerful hydraulic press," so arranged as to " indicate 
accurately the amount of pressure." Not having witnessed any 
of the experiments or the arrangements of the machine, the 
writer feels bound to say that these allegations respecting the 
machine have been published by the architect, by the superin- 
tendent, and by others concerned in building the monument at 
Washington. These experiments were communicated to the 
writer by Dr. Page. 

Crushing weight in pounds per square inch. 



No. of the trial. 
1. 

2. 
3. 

4. 

5. 

6. 

7. 

8. 

9. 
10. 
11. 



910 
1372 

2281 
2312 
2437 
2531 
2625 
2650 
2750 
2843 
2968 

2334 



Average strength, 

Note. — From the above it appears that the greatest strength 
per square inch, when tested in two inch cubes is 2968 pounds, 
and the least 910 pounds, the latter being about 30 per cent, of 
the former number. 

2. Trials by Dr. Page, of other building materials to obtain 
results, on two-inch cubes, comparable with those afforded by 
the "alum limestone." 



No. of trial. 



Kind of stone. 



Crnshing weight in 
lbs. per square inch. 



Fine-grained marble of Symington, . . 4562 

Another sample of do. . . . 4400 

White veined marble, East Chester, N. Y., used 

at the General Post Office, . . .4081 

do. another specimen, .... 3906 



Italian marble, 



3156 



Experiments on American and Foreign Building Stones. 9 

Crushing weight In 
No. of trial. Kind of stone. lbs. per. square incli. 

6. Patapsco granite, 2941 

7. do. another specimen, . . . 2593 

8. Seneca sandstone, (Smithsonian building,) . 2691 

9. do. do. another specimen, . . 2691 
10. Stockbridge marble, Mass., . . . .2410 

[11. Alum limestone, [casing of monument,) average 

as above, ....... 2334] 

12. Stockbridge marble, 2d specimen, . . . 2093 

13. York road freestone, (a friable brown sandstone,) 2125 

14. Aqnia Creek sandstone, (Patent Office,) . . 2093 

15. do. do. do. 2d specimen, . . 1875 

16. do. do. do. 3d do. . . 1441 

17. do. do. do. 4th do. . . 1234 

18. Common building brick, .... 1000 
Arranging in order of the average strength, we have the follow- 
ing succession, a column of relative values being added in which 
the alum limestone is represented by 100, 

Average strength 

1. Maryland fine-grained marble, . 

2. East Chester (N. Y.) marble, 

3. Italian marble, .... 

4. Patapsco granite, 

5. Seneca (Smithsonian) stone, 
[6. Alum limesto?ie (monument), 

7. Stockbridge marble, . 

8. York-road freestone, . 

9. Aquia Creek (Patent Office) sandstone, 
10. Common brick, .... 

Note. — The two sandstones, numbers 5 and 8, have a mean 
strength of 2408, which is three per cent, higher than that of 
the " alum limestone," which has its place between them in the 
above series. The four trials of the Aquia Creek sandstone give 
an average strength of 1660 pounds, an-d the first three experi- 
ments of Dr. Page on the alum limestone gave an average of 
1521 pounds, showing the inferiority of at least some portions of 
this limestone to that " material which now disfigures the archi- 
tecture of the Treasury building and the Patent Office."* 

3. Experimejits on different building materials, published hy 
Mr. Robert Mills, architect of the Washington National Monu- 
ment. Specimens of the same size as the preceding. 

Strength per Relative 
No. of trial. Kind of stone. square inch. value. 

1. Symington's fine-grain marble, . . 6344 271- 

2. Baltimore granite (Sumwalt and Grayson's), 6250 267- 

* Hints on Public Architecture, p. 114. 



er square inch. 


Relative value. 


. 4481 


192 


. 3993 


171 


. 3156 


135 


. 2767 


118 


. 2691 


115 


. 2334 


100] 


. 2251 


96 


. 2125 


91 


!, 1660 


71 


. 1000 


42 



10 Experiments on American and Foreign Building Stones. 



No of trial. 



3. 



Kind of stone. 



Strengtii per Relative 
square inch. value. 



Blue rock from Potomac, used as the back- 
ing stone of the National Monument, 3750 160 

4. Granite of the east {Port Deposit), , 3250 139 

5. Granite of Normandy * . . . 2628 112 
[6. Alum limestone (monument), . . 2334 100] 

4. Marbles and limestones tested and Reported on hy Mr. 
Rennie in England.-\ 

Lbs. per Rplative 
No. of trial. Kind of stone. sq. inch. value. 

1. White Italian veined marble (tried in IJ 

inch cubes), ..... 

2. Black Brabant marble (tried in IJ in. cubes, ^ 

3. Purbeck stone, do., 

4. Black compact limestone. Limerick, Ireland, 

(tried in IJ inch cubes,) . 

5. Compact limestone, do., . 

6. Devonshire red marble, do., 

7. White statuary marble, not veined, do., 

8. White Italian veined marble, tried in one- 
inch cubes, ..... 



9281 


395 


9160 


392 


8855 


379 


7713 


330 


7187 


308 


6058 


259 



[9. Alum limestone, (as above, ) 



3216 137 
2334 100] 

Note. — From his own reading of the original memoir of Mr. 
Rennie, the writer was led to suppose that all the above samples 
of stone, numbered from 1 to 6 inclusive, had been tested in two- 
inch cubes, and that the Numbers in the Philosophical Transac- 
tions ( 1818) referred to blocks of four square inches on the base ; 
but in the Encyclopedia Britannica Mr. Tredgold has given the 
dimensions 2-25 square inches for the base. Barlow has appa- 
rently understood Mr. Rennie in the same way. On this latter 
area the above numbers are computed. On the supposition of a 
four-inch base they would stand as follows : — 



No. 1. gave per sq. inch 5445 lbs. 
" 2. " '' 5185 " 

" 3. " '' 5152 '•' 



No. 4. gave per sq. inch 4981 lbs. 
'' 5. " " 4338 '' 



These numbers change the relative values but they do not 
alter the position of the " alum limestone," which stands, as 
proved by Dr. Page, far below all the hmestones and marbles, 
tested by Mr. Rennie, whether the latter were in 1, 1^ or 2-inch 
cubes. 



* See below some account of other granites of Normandy, tried in two-inch cubes 
by llondelet. 

I Transactions Royal Society, 1818. 



Experiments on American and Foreign Building Stones. 1 1 



5. Experiments hy Mr. Rennie on granites, tested in 1 J inch 
cubes. 



1. Aberdeen blue granite, 

2. Peterhead hard close grained granite, . 

3. Cornish granite, .... 
[4. Alum limestone, as above, . 

6. Mr. Rennie's experiments on sandstones. 



Lbs. per 
sq. inch. 

10,913 

8,2S2 
6,356 
2,334 



Lbs. per 
sq. inch. 



Relative 
value. 

46r 

354 

272 
100] 



Relative 
value. 



1. Very hard freestone (IJ-inch cubes), . 9446 404 

2. Dundee sandstone, breccia, do. . . 6630 284 

3. Bramley falls sandstone near Leeds, do. . 6063 259 

4. Craigleith white freestone, do. . . 5487 234 

5. Portland stone, do 4570 195 

6. Killaly white freestone, do. . . . 4561 195 

7. Derby grit red friable sandstone, average of 
two varieties, do. . 

Portland stone in a 2-inch cube, . 
Alum limestone, as before, . 
Note. — The weakest of the above 
stronger than the strongest specimen 
tried by Dr. Page. 

7. Experiments hy Messrs. Daniel and Wheatstone, on the 
magnesian limestone of Yorkshire, Derbyshire and Nottingham- 
shire in England, employed in building the new Houses of Par- 
liament.* Tested in two-inch cubes, in duplicate. 



1. Stone of Kiveton, 



8. 
[9. 



3743 
3729 
2334 

sandstones is 27 per cent, 
of the " alum limestone'^ 



160 
159 
100] 



Stone-ends, 

Bolsover Moor, . 

Kiveton, 2d variety, 

Norfall, 

Steetley, yellow variety, 

Steetley, white do. . 



Lbs. per 
sq. inch. 


Relative 
value. 


0,695 


458 


9,209 


394 


8,288 


355 


6,163 


284 


5,879 


252 


5,171 


221 


3,192 


136 


2,334 


100] 



[8. Alum limestone of Mai^yland, as before. 

Note. — The average strength of the seven varieties of stone 
above compared is exactly three times as great as that of the 
"alum limestone." 

The stone used for the houses of Parliament is described as 
standing, in its natural site, high above the ground, in large masses 
or perpendicular walls, with its smooth, bleached, tmie-worn 
surface, discolored only by a few lichens with a little moss or 
ivy, — facts clearly indicating its strength and durability. 

* See " Lithology, or observations on stone used for building," by C. H. Smith, p. 22. 

2 



;. per. sq. inch. 


Relative val 


11,2]8 

5,738 


480 
245 


4,652 

4,328 
4.241 


199 

185 
181 


3,701 
2,334 


158 
100] 



12 Experiments on Atnerican and Foreign Building Stones. 

8. Experiments on Marbles^ made in France by Rondelet, Gau- 
they, Svfflot and Perronet^ on two inch cubes, the weights and 
measures being reduced to Enghsh to conform to the other 
series. 

1. Black marble of Flanders, . 

2. Oervelas marble of Flanders, 

3. White Statuary marble, 

4. Bkie Turquin marble, . 

5. Veined white marble, . 

6. Veined white marble called Pauf, 
[7. Alurn limestone of Md., as above, 

Note. — With the exception of the first of the above trials the 
French experiments conform pretty nearly with those of Mr. 
Rennie on similar materials supposing the numbers given by the 
latter were obtained from two inch cubes; but they fall far below 
his results, admitting, with Tredgold, that his blocks were IJ 
inch cubes. Gregory appears to have understood that all Ren- 
nie's experiments were made on IJ inch cubes unless otherwise 
expressly stated. 

9. Experiments of Hondelet and other French experimenters 
on two-inch cubes of granite. 

Lbs. per. sq. inch. Relative value. 

1. Oriental rose granite, . . 12,518 536 

2. Granite of Normandy called 

Champ du Bout, . . 11,628 498 

3. Granite of Normandy called 

Gallicien, .... 

4. Granite of Bretagne. 

5. Green granite of Vosges, 

6. Beola granite used in Milan, . 

7. Grey granite of Vosges, . 
[8. Alum limestone of Maryland, 

The average relative value of the seven granites above cited is 
396, or almost four times that of the "alum stone." 

10. Experiments 07i stones used in the construction of various 
ancient edifices, reported by Rondelet, — size two inch cubes. 

Lbs. per. sq. inch. Relative value. 

1. Caserte stone of Italy, . . 8,584 363 

2. Stone of Istria used by Palladio, San- ^ 

covino and Scamozze in the edi- > 7,395 316 

fices of Venice and Vicenze, ) 

3. Fourneaux stone, pillars of All Saints 

Church at Angers, . . 6,317 270 

* Trait6 theorique et pratique de I'ai-t do Mtir. Par Jean Rondelet, torn. i. p. 
211-214. 



9,987 
9,303 

8,798 
6,603 


428 
398 
376 

282 


6,020 
2,334 


257 
100] 



29,549 


1266 


28,455 


1219 


27,196 


1165 


25,172 


1078 


16,416 


703 


2.334 


100] 



Experiments on American and Foreign Building Stones. 13 

Lbs. per sq. inch. Relative value. 

4. Grey stone of Florence, . . 6,096 261 

5. Stone of the bridge of St. Maxence, 5,404 231 

6. Travertin, material of ancient Roman 

buildings, .... 4,301 183 

7. Bagneanx stone, columns of the Pan- 

theon, Paris, . . . 3,484 149 

8. Stone of the temple of Paestum, 3,258 130 
[9. Alum limestone, Maryland, . 2,334 100 •] 

The average relative value of these ancient building stones 
is 238. 

11. Experiments on two-inch cubes of Basalt and Porphyry, 
by Gauthey and Rondelet^ reported by the latter in the work 
above cited. 

Lbs. per sq. inch, (Eng.) Relative value. 

1. Basalt of Auvergne, 

2. Porphyry, 

3. Swedish basalt, 

4. Basalt of Auvergne, 2d variety, 

5. do. do. 3d variety, 
[6. Alum limestone, 

The average relative value of the basalts and porphyries is 1086. 

12. Experiments on the ahnn limestone of Maryland in blocks 
of other dimensions than two inch cubes, published by Mr. 
Dougherty, the Superintendent of the Washington National Mon- 
ument, as having been made at the Navy Yard, Washington. 

Per square inch of base. Average. 

1. A 1-inch cube (1 sq. inch base), 2000 

2. Another block of the same size, do. 2000 Espt. 1 and 2,-2000 

3. A cube of 3^ inches on a side, (12^ base.) 3265 

4. Another cube of same size, do. 3765 Espt. 3 and 4, — 3515 

5. A slab 4| inches square, 2 inches thick, (22-56 base,) 5629 

6. do. 4| square, 4| inches high, do. 2659 

7. A 4-inch cube, (16 inch base,) 5687 Expt. 5 and 7, — 5658 

The 6th experiment is alledged to have been made on a block 
of unequal thickness and therefore not to give a fair result. 

The first two of the above experiments give results considera- 
bly below the average of Dr. Page's trials on two-inch cubes. 
The only standard with which we can at present compare them, 
is the one inch cube of Italian veined marble tried by Mr. Ren- 
nie, which gave 3216- lbs. per square inch. Their relative values, 
by this comparison, are 100 and 160. Comparing the three aver- 
ages above given, there is an evident increase of strength per 
square inch of base, dependent apparently in some measure on the 
increased size of the specimens. 

We are furnished by the paper of Mr. W. Wyatt of England, 
with a considerable series of experiments on marbles, granites. 



14 Experiments on American and Foreign Building Stones. 

and sandstones, tested in cubes of about the same size as the 
largest of those above given. His investigations were made with 
the aid of the hydrauHc press of Messrs. Bramah & Sons, and in 
this respect also appear to be comparable with those, made on 
the ahim limestone in large blocks. Each of his results is the 
mean of two trials*. 

13. Mr. Wyatfs experiments on marbles, in blocks of larger 
size than 2-inch cubes. 

Lbs. pr. sq. inch. Rel. value. 

1. Ravaccioni marble, (blocks 4-^-^X 4 inches base), . . .9632 172 

2. Veined marble ( " 4iX4 "... 9251 163 
[8. Alum limestone in 4, and in 4|- inch cubes (average), . 5658 100] 

From the above and the preceding series of trials, it appears 
that the ^^ alum limestone''^ falls very far below Italian marble, 
whether tested in 1-inch, 2-inch, or 4-inch cubes, and whether 
crushed under a hydraulic press, or any of the other carefully 
constructed machines which have been employed for the purpose 
in France and England. Compared with every other good mar- 
ble and limestone, its inferiority of strength, when the size of 
cubes was the same, appears still more remarkable. 

14. Mr. Wyatfs experiments on granites tested in cubes of 4 
inches on a side, or in blocks of which the base measured 45 by 
4 inches. 

1. Herm granite, (4-inch cubes), . 

2. Heytor do. do. 

3. Dartmoor granite, do. 

4. Peterhead red do. (4*5x4 inch base), 

5. Aberdeen blue do. (4-25x4 do.) . 

6. Peterhead blue gray do. (4-5 x 4 do.) 

7. Penryn granite, (4-5 X 4 do.) . 
[8. Alum limestone, (in 4 and in 4| cubes), 

15. Mr. Wyatfs experiments on sandstones, 
of 5^ and 6 inches on a side. 

Lbs. pr. sq. inch. Rel. val. 

1. Yorkshire Cromwell stone (55 inch cubes) 8,825 156 

2. Craigleith stone (6 inch cubes). . . 6,652 117 

3. Humbie stone do. ... 4,614 81 

4. Whitby sandstone do. ... 2,374 41 
[5. Alum limestone {im\dii-7 5 c\\\)Qs), . . 5,658 100] 

The average strength of the above four sandstones is almost 
identical with that of the alumstone, as given by these experi- 
ments. Had the cubes been 4 instead of 6 inches, the compari- 
son might probably have been more favorable to the alumstone. 
Its true position in the scale of strength, among building stones, 



Lbs. pr. sq. inch. 


Rel. value 


. 14,873 


262 


. 13,865 


245 


. 12,275 


217 


. 10,931 


193 


. 10,393 


183 


. 9,766 


172 


. 7.728 


136 


. 5,658 


100] 



tested in cubes 



See Transuctious of the Society of Civil Engineers, voL i, p. 235. 



Experiments on American and Foreign Building Stones. 15 

as proved both by Dr. Page and Mr. Wyatt, is among the sand- 
stones, not among granites, marbles or compact hmestones. 

16. In addition to the foregouig comparisons, the writer is en- 
abled to add two experiments of his own on the Q,uincy syenite, 
the stone of which the Banker Hill Monument is built. These 
experiments were made July 28, 1843. 

Lbs. pr. sq. inch. Rel. value. 

1. A 1-5 inch cube (2-25. sq. inch base), bore . . . 15,929 682 

2. A block having a base 2'5Xl'15=2-87 sq. inches and a 

length of 0-25 inches, proved endwise, bore . . 12,390 530 

[3. Alum iinicstone — Dr. Page's trials on 2 inch cubes, . 2,334 100] 

Note. — The block proved by compressing it endwise was not 
crushed, but only splintered or slightly "spalled" along the cor- 
ners. This was done at two successive apphcations of the same 
compressing force. The 1*5 inch cube was crushed with the 
force above given. 

From these experiments it appears that the Bunker Hill Monu- 
ment stone is possessed of a strength intermediate between Orien- 
tal rose granite, and Auvergne basalt, as given by M. Rondelet. 

That a coarse, loosely aggregated rock like the alumstone, is 
far inferior in strength to rocks of the same chemical constitution 
and specific gravity but of fine texture, was long since proved 
by Rondelet. We may cite one or two of his proofs and add by 
way of comparison, two others derived from the preceding sec- 
tions of this paper. 

] 7. Experiments on coarse, and on Jine-grained stones of the 
same class. Specimens tried in two-inch cubes. 

, j Roussard stone, coarse grained, 395*7 

Choin de Villeburg, jine grained, 8300 

Saiilan court stone, coar&e grain, ....... 2062 

Stones of Passy and Vaugirard, fine grain, .... 4484 

o ( Symington's coarse a?z<m /w^estowe, (11 trials by Dr. Page,) . 2334 

' ( Symington's fine grain marble, (2 do. do. . , 4484 

. j Alum limestone, highest of Dr. Page's results, . . . 2968 

■ ( Fine grain marble, highest result by Mr. MUls, .... 6344 

The average strength of the four coarse-grained stones is 
2830, that of the four fine grained ones, 5982. The ratio of 
these numbers is 100 to 211. 

Arranging the several kinds of stone in the order of their rela- 
tive values as determined by their power to resist crushing, and 
placing against each the number of square inches on the base of 
the specimens tried, with the name of the experimenter, we have 
the following rank, as indicated by a comparison with the alum 
limestone used in casing the Washington National monument, 
the strength of which is taken as 100. 



16 Experiments on American and Foreign Building Stones. 



No. 



Name of stone. 



Basalt of Auvergiie, 

Porphyry, 

Swedish basalt, 

Auvergne basalt, 2d variety, 

do. do. 3d variety, 

Quincy syenite, 1^ inch cube, 

Oriental rose granite, 

Quincy syenite, long block, 

Granite of IS'ormandy, Champ du Bout, 

Black marble of Flanders, 

Aberdeen blue granite, 

Kiveton dolomite, 

Granite of l!^ormandy, Gallicien, 

Wiiite Italian veined marble, 

Very hard freestone, 

Granite of Bretagne, , 

Brabant black marble, 

Dolomite from Stonends, 

Purbeck stone, 

Compact black limestone of Limerick, . 

Green granite of Vosges, 

Caserte stone of Italy, 

Bolsover Moor dolomite, 

Peterhead close-grained granite , 

Compact limestone, , 

Istria stone, 

Devonshire red marble, , 

Kiveton dolomite, 2d variety, , 

Dundee sandstone, 

Beola granite, Milan, 

Cornish granite, 

Symington's fine-grained stone, 

Fourneaux stone. Angers, , 

Baltunore granite, 

Herm granite, , 

Greystone of Florence, , 

Bramley Falls sandstone, Leeds, 

Statuary marble not veined, 

Grey granite of Vosges, , 

Norfall dolomite, 

Heytor granite 

Cervelas marble of Flanders, 

Craigleith white freestone, 

Bridge of St. Maxence stone, 

Steetley yellow dolomite, 

Dartmoor granite, 

White statuary marble, 

Portland stone, . . , 

Killaly white freestone, 

Peterhead red granite, 

Symington's Maryland fine-grained stone, 

Blue Turquin marble, 

Travertin of Ancient Rome, 

Aberdeen blue granite, 

Veined wliite marble, 

Peterliead bluo-grcy granite, 

Ravaccioni mar})le, 

Kast Chester marble, N. Y., 

Veined marble 



Area of 
base ofspe 
cimens in 
sq. inches 



4 

4 

4 

4 

4 

2-25 

4 

2-8'7 

4 

4 

2-25 (?) 

4 

4 

2-25 (?) 

2-25 

4 

2-25 (?) 

4 

2-25 (?) 

2-25 (?) 

4 

4 

4 

2-25 (?) 

2-25 (?) 

4 

2'25(?) 

4 

2-25 

4 

2-25 

4 

4 

4 
16 

4 

2-25 

2-25 

4 

4 
16 

4 

2-25 

4 

4 
16 

4 

2-25 

2-25 
18 

4 

4 

4 
17-5 

4 
18 
18 

4 
18 



Name of experimenter. 



Rondelet, 

do 

do 

do 

do 

Johnson, 

Rondelet, 

Johnson, 

Rondelet, 

do 

Rennie, 

Daniel & Wheatstone 

Rondelet, 

Rennie, 

do 

Rondelet, 

Rennie, 

Daniel & Wheatstone, 

Rennie, 

do 

Rondelet, 

do 

Daniel & Wheatstone, 

Rennie, 

do 

Rondelet, 

Remiie, 

Daniel & Wheatstone. 

Rennie, 

Rondelet, 

Rennie, 

Mills, 

Rondelet, 

Mills, 

Wyatt, 

Rondelet, 

Rennie, 

do 

Rondelet, 

Daniel &, Wheatstone. 

Wyatt, 

Rondelet, 

Rennie, 

Rondelet, 

Daniel &, Wheatstone 

Wyatt, 

Rondelet, 

Rennie, 

do 

Wyatt, 

Page, 

Rondelet, 

do 

Wyatt, 

Rondelet, 

Wvatt, 

do 

Page 

iWvatt, 



Rel. val. 
Alnm- 
stone = 

100. 



1266 
1219 
1165 
1098 
703 
682 
536 
530 
498 
480 
467 
458 
428 
414 
404 
398 
395 
394 
392 
379 
376 
363 
355 
354 
330 
316 
308 
284 
284 
282 
272 
271 
270 
267 
262 
261 
259 
259 
257 
252 
245 
245 
234 
231 
221 
217 
199 
195 
195 
193 
192 
185 
183 
183 
181 
172 
172 
171 
103 



Experime7its on American and Foreign Building Stones. 17 



Table continued. 



Name of stone. 



Area of . 

cfmenl'^Tn, ^^"^^ "^ experimenter. 

sq. inches. I j JOO. 



Rel. val.! 
Alum- I 

stone =1 



" Metamorphic blue Potomac stoue, 

Derby grit, friable sandstone, 

Portland stone, 

Veined white marble, (Pauf,) 

Yorksliire Cromwell stone, 

Bagneaux stone, (Paiitheon at Paiis,) .... 

Granite of Port Deposite, 

Wliite veined Italian marble, 

. Steetley white dolomite, 

Penr^ai granite, 

. Itahan marble, 

Temple of Paestum stone, 

Patapsco granite, 

Craigleith sandstone, 

Seneca sandstone, Smithsonian Institute, . 

Granite of Wormandy, 

Alum limestone, ( Wash'gton^Nat'nal.Mon't.) 

|Stockbridge marble, 

iTork road brown sandstone, 

jHmiibie sandstone, 

Aqiiia Creek (Patent Ofl&ce) sandstone, . . 
! Whitby sandstone, 



2-25 

2-25 

4 

4 
30-25 

4 

4 

1 

4 
18 

4 

4 

4 
36 

4 

4 

4 

4 

4 
36 

4 
36 



Mills, 

Rennie, 

do 

Rondelet, 

Wyatt, 

Rondelet, 

MiUs, 

Rennie, . •. 

Daniel & Wheatst'ne 

Wyatt, 

Page, 

Rondelet, 

Page, 

Wvatt 



Mills, . . 
Page, . . 

do. .. 

do. .. 
Wyatt, 
Page, . , 
Wvatt, 



112 
100 
96 
91 
81 
11 
41 



The wide discrepancy already noted between the results ob- 
tained in experimenting on the alum limestone, in which the 
pressure required for crushing varied from 910 pounds to 5687 
pounds per square inch of the area of the base, must be explained 
either on one or the other of three suppositions; 1st, that the 
strength of different specimens of the rock is thus variable, 
and that consequently no certain reliance could be placed on its 
pov\^ers of resistance ; or 2nd, that the experimenting or the 
machine with which it was conducted Avas faulty ; or 3rd, that 
the resistance to crushing for a unit of area at the base, in- 
creases in some ratio with the number of units composing that 
area, that is, with the actual area of the base. The experiments 
published by Mr. Dougherty show discrepancies nearly as wide 
as those previously made by Dr. Page, beginning however with 
2000 pounds on a one-inch cube, and ending with 5687 pounds 
per square inch on a four-inch cube, instead of beginning with 
910 pounds and ending with 2968 pounds on two-inch cubes. 

With a view to trace some relation, if such exist, between the 
increase of area of base and the power of resistance of cubes of 
granular rocks and other materials, the writer has proposed a se- 
ries of trials on several stones, in cubes of different sizes from one 
to six inches on a side, all those of the same kind of stone to be 
taken from the same block and accurately reduced to the re- 
spective dimensions. At present the following comparisons seem 
to point to a direct relation between the power of resistance of 
the cube and the product of the ai^ea of the base multiplied into 
the cube root of that area. 



18 Experiments on Ainerican and Foreign Building Stones. 

1. The one-inch cubes of alum h'mestone gave Mr. Dougherty 
two thousand pounds, and the 4-75 inch cube, having 22-56 square 
inches on the base, gave 5629 pounds per square inch. In com-, 
paring these with the cube roots of the areas of base we have 
Vl : 1/22^ : :2000 : 5652 or the calculated exceeds the experi- 
mental result by only twenty three pounds, or 4 per cent. 

2. A two-inch cube of the alumstone in Dr. Page's third 
experiment gave per square inch of base 2281 pounds, and a 
3J inch cube in Mr. Dougherty's third experiment, gave 3265 
pounds per square inch. Comparing these we have VA : X/ 12-25 
::2281 : 3312 showing that the calculated exceeds the experi- 
mental result by 47 pounds or about one and a half per cent. 

3. The seventh experiment of Dr. Page gave 2625, and the 
fourth of Mr. Dougherty gave 3765, consequently \/4 : V [2-25 
: ;2625 : 3812, in which the calculated exceeds the experimental 
by forty-two pounds, or \j\ per cent. 

4. Mr. Dougherty's first and second experiments on one inch 
cubes gave 2000 pounds, and Dr. Page's eleventh experiment on 
two-inch cubes gave 2968. Hence v^I : \/4 : 2000 : 3156 
where calculation exceeds experiment by two hundred and seven 
pounds, or 6-9 per cent. 

5. Comparing Dr. Page's eleventh experiment with Mr. Dough- 
erty's fifth, in which a block 4f inches on a side bore 5629 pounds 
per square inch, we have \/4. : t/22-56: :2968 : 5283, in which 
calculation falls short of experiment by 346 pounds or about 6 
per cent. 

6. Mr. Rennie's eighth trial on marbles, showed that a one 
inch cube of white Italian marble bore 3216, and M. Rondelet on 
a two inch cube of the same, obtained per square inch, 4651 
pounds. Hence Vl : v^l: :3216 : 5106, the calculated exceed- 
ing the experimental result by 455 pounds, or nearly 9 per cent. 

7. By our reading of Mr. Rennie's memoir, he obtained from a 
two inch cube of Italian veined marble, 5445 pounds per square 
inch, and Mr. W"yatt obtained from a 4^ by 4 inch block, 9251 
pounds. Here, VI : v/18 : :5445 : 8990 differing in defect from 
the experimental result by 261 pounds, or less than 3 percent. 

8. If Mr. Rennie's experiment on Aberdeen granite was, as 
we suppose, also on a two inch cube, its strength per square inch 
was 6139 pounds, and as Mr. Wyatt obtained from Aberdeen 
granite, when tried in blocks 4 J x 4 inches on the base, a strength 
of 10,393 pounds, we have Vl : v/IS::6139 : 10130 where 
the calculated falls short of the experimental result by 263 pounds 
~2i per cent. 

9. Mr. Rennie proved Cornish granite in one and a half inch 
cubes to have a strength per square inch of 6356, and IMr. Wyatt 
on a four inch cube of Dartmoor granite, obtained 12,275 pounds. 



Experiments on American cmd Foreign Building Stories. 17 

Now l^2r25 : v^lG: :6356 : 12,420 making the calculated to ex- 
ceed the experimental result by 145 pounds or lyV per cent. 

10. Mr. Rennie tried five blocks of cast iron of ^th inch square 
base and Jth to f th high and found the crushing force 1710 pounds 
per one-eighth. He also tried thirteen cubes of Jth inch, and found 
the average 2600 pounds per one-eighth inch base. In this case 
•v/I : a/4:: 1710 : 2712, showing the calculated to exceed the 
experimental result by 112 pounds, or about 4 per cent. 

It is not alledged that these ten cases conclusively establish the 
law, but they seem to afford a pretty strong presumption in its 
favor : and though it is true that these cases are for want of cer- 
tainty as to the perfect similarity of specimens compared, liable to 
some objection, yet they appear to warrant a series of experi- 
ments of the kind above proposed. Should the law not be 
thereby confirmed, one of the other explanations of the discrepan- 
cies in the strength of " alum limestone" must be resorted to. 



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